This invention relates to the necessity of establishing and measuring perpendicularity of the spindle of a vertical or horizontal machine tool as it relates to the table, work-holding or tool-holding surface of the machine.
The prior art to manually establishing perpendicularity of a machine tool spindle to the workholding axis has traditionally been accomplished through labor intensive means. Perpendicularity must be established and quantifiably measured prior to setting up a manually operated spindle-type machine tool in order to verify the correct position of the workholding surface to the tool-holder. If the spindle is not aligned to the point at which 0.001 or less graduated dial indicator swept readings are identical at various points in the circumference the work-holding surface area, the quality of any work performed can be severely compromised or even rejected. Wozniak clearly describes the painstaking task of zeroing or squaring the head of a vertical milling machine in his patent (see U.S. Pat. No. 5,253,425, Wozniak, October 1983, Description of Prior Art, Par. 4.)
The drawbacks besides the obvious laboriousness of the prior at in squaring the spindle of a machine tool to its workholding surface are as follows: (a) The cumbersome nature of using a plurality of gauges and fixtures which must be assembled prior to use and dis-assembled after use; (b) The excessive amount of time needed to accomplish the task (as Wozniak states and as affirmed by other journeymen machinists 45 minutes to accomplish this using prior art method is considered average); (c) The physical discomfort using the prior art method which requires the machinist to hold one arm extended while repeatedly bending downward to observe the readings on the indicator for a prolonged amount of time; (d) The necessity of having to perform the task of squaring the head each and every time a new project is to be set up on the machine which may be numerous times each day or week depending on the schedule of work in the shop; (e) The back-up of work flow because of the lengthy nature of squaring the head of the spindle; (f) The necessity of having to utilize experienced machinists to perform a task which is, by its nature, time consuming and non-productive.
The design of manually operated spindle machines such as milling machines also complicate the process of squaring the spindle. These machines have anxe2x80x9coff-centerxe2x80x9d pivot making it troublesome for even an experienced machinist to square since it is difficult to judge to amount of adjustment require to bring the spindle of the machine into a perpendicular position because of the angular position of the pivot in relation to the head and table. Generally, the accepted rule of thumb is that the head of the machine should be perpendicular to the workholding surface within 0.0005 inches in 6 inches (0.013 mm in 15.24 cm). However, frequent and time consuming adjustments are required since even the slightest movement may extrapolate into major misalignments because of the off-center nature of the machine tool""s pivot.
Another variable which is difficult to negotiate in aligning the spindle to the workholding surface is the amount of play in the gears of the machine tool""s spindle head. Since these machine tools have useful lives of well over ten years, normal usage causes the gears to wear. While this may not compromise the performance of the machine once it is properly squared and set-up, it does complicate the process of squaring the spindle head. At this point, the process of squaring the head can become more of an intuitive art than a mechanical one, with the machinist oftentimes guessing at the amount of alignment necessary to accommodate the unknown level of play in the gears.
The present invention provides a self-contained unit with features for permanently mounting measurement gauges eliminating the need for repetitious assembly and dis-assembly.
Once assembled, the unit is self-calibrating.
This device effectively eliminates the variable of xe2x80x9cplayxe2x80x9d in the gears of the spindle head of the machine tool.
The direction of adjustment which the machinist must make is readily known and a measurable reading can be taken without having to tram the device.
The ease of use enables apprentice or entry-level employees to successfully tram or square the spindle head of a machine tool and its efficiency eliminates physical discomfort caused by the prior art.
The amount of time to square a spindle head machine utilizing this device is far less than the prior art.
This device allows standard tramming operation for confirmational readings without the need of a secondary device.
This device accurately squares the head of the spindle to any workholding surface or fixture that may be bolted to the table.
This device accurately calibrates the spindle head to known angles or compound angles when used with a sine bar or gauge block.
This device is lightweight and easily stored as a personal tool unlike the prior art tools which are cumbersome, bulky, and require multiple, unrelated components.
To the inventors"" knowledge comprised of over 60 years cumulative experience in this field, no such device such as the present invention exists.